Establishing a temperature gradient through a centimeter thick membrane is generally done by heating one side and/or cooling the other. An insulator can be placed between the two sides to increase efficiency. One way of establishing a temperature gradient of 1000° C. through a 1 cm thick membrane is to make the membrane out of a layer of steel and aerogel. When the surface of the steel is heated up to 1000° C., the surface of the aerogel will stay around room temperature for some time.
However the thickness of the membrane decreases, it becomes harder to form and maintain such gradients. In fact if one were to consider the ratio of 1000° C. per centimeter, this equates to 0.001 degrees per 100 nanometers. Such a temperature gradient has very few uses. However, establishing a 0.5° C. gradient over 100 nanometers would be equivalent to having a membrane of 1 cm thickness with room temperature on one side and the surface of the sun on the other.
There are several exotic ways of maintaining a temperature gradient at such small scales, mostly involving the implementation a cavity with vacuum as an insulator and using the Peltier effect or thermionic emission to establish the temperature bias. However such devices are relatively large, most of them appearing to be thicker than 10 microns.
To establish and maintain a temperature bias among a plurality of points in a membrane where such temperature bias is necessary, where the desired temperature bias over a distance of 10 microns or less in particular, new methods and devices appear to be necessary.